1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * inode.c 4 * 5 * Copyright (c) 1999 Al Smith 6 * 7 * Portions derived from work (c) 1995,1996 Christian Vogelgsang, 8 * and from work (c) 1998 Mike Shaver. 9 */ 10 11 #include <linux/buffer_head.h> 12 #include <linux/module.h> 13 #include <linux/fs.h> 14 #include "efs.h" 15 #include <linux/efs_fs_sb.h> 16 17 static int efs_read_folio(struct file *file, struct folio *folio) 18 { 19 return block_read_full_folio(folio, efs_get_block); 20 } 21 22 static sector_t _efs_bmap(struct address_space *mapping, sector_t block) 23 { 24 return generic_block_bmap(mapping,block,efs_get_block); 25 } 26 27 static const struct address_space_operations efs_aops = { 28 .read_folio = efs_read_folio, 29 .bmap = _efs_bmap 30 }; 31 32 static inline void extent_copy(efs_extent *src, efs_extent *dst) { 33 /* 34 * this is slightly evil. it doesn't just copy 35 * efs_extent from src to dst, it also mangles 36 * the bits so that dst ends up in cpu byte-order. 37 */ 38 39 dst->cooked.ex_magic = (unsigned int) src->raw[0]; 40 dst->cooked.ex_bn = ((unsigned int) src->raw[1] << 16) | 41 ((unsigned int) src->raw[2] << 8) | 42 ((unsigned int) src->raw[3] << 0); 43 dst->cooked.ex_length = (unsigned int) src->raw[4]; 44 dst->cooked.ex_offset = ((unsigned int) src->raw[5] << 16) | 45 ((unsigned int) src->raw[6] << 8) | 46 ((unsigned int) src->raw[7] << 0); 47 return; 48 } 49 50 struct inode *efs_iget(struct super_block *super, unsigned long ino) 51 { 52 int i, inode_index; 53 dev_t device; 54 u32 rdev; 55 struct buffer_head *bh; 56 struct efs_sb_info *sb = SUPER_INFO(super); 57 struct efs_inode_info *in; 58 efs_block_t block, offset; 59 struct efs_dinode *efs_inode; 60 struct inode *inode; 61 62 inode = iget_locked(super, ino); 63 if (!inode) 64 return ERR_PTR(-ENOMEM); 65 if (!(inode->i_state & I_NEW)) 66 return inode; 67 68 in = INODE_INFO(inode); 69 70 /* 71 ** EFS layout: 72 ** 73 ** | cylinder group | cylinder group | cylinder group ..etc 74 ** |inodes|data |inodes|data |inodes|data ..etc 75 ** 76 ** work out the inode block index, (considering initially that the 77 ** inodes are stored as consecutive blocks). then work out the block 78 ** number of that inode given the above layout, and finally the 79 ** offset of the inode within that block. 80 */ 81 82 inode_index = inode->i_ino / 83 (EFS_BLOCKSIZE / sizeof(struct efs_dinode)); 84 85 block = sb->fs_start + sb->first_block + 86 (sb->group_size * (inode_index / sb->inode_blocks)) + 87 (inode_index % sb->inode_blocks); 88 89 offset = (inode->i_ino % 90 (EFS_BLOCKSIZE / sizeof(struct efs_dinode))) * 91 sizeof(struct efs_dinode); 92 93 bh = sb_bread(inode->i_sb, block); 94 if (!bh) { 95 pr_warn("%s() failed at block %d\n", __func__, block); 96 goto read_inode_error; 97 } 98 99 efs_inode = (struct efs_dinode *) (bh->b_data + offset); 100 101 inode->i_mode = be16_to_cpu(efs_inode->di_mode); 102 set_nlink(inode, be16_to_cpu(efs_inode->di_nlink)); 103 i_uid_write(inode, (uid_t)be16_to_cpu(efs_inode->di_uid)); 104 i_gid_write(inode, (gid_t)be16_to_cpu(efs_inode->di_gid)); 105 inode->i_size = be32_to_cpu(efs_inode->di_size); 106 inode->i_atime.tv_sec = be32_to_cpu(efs_inode->di_atime); 107 inode->i_mtime.tv_sec = be32_to_cpu(efs_inode->di_mtime); 108 inode_set_ctime(inode, be32_to_cpu(efs_inode->di_ctime), 0); 109 inode->i_atime.tv_nsec = inode->i_mtime.tv_nsec = 0; 110 111 /* this is the number of blocks in the file */ 112 if (inode->i_size == 0) { 113 inode->i_blocks = 0; 114 } else { 115 inode->i_blocks = ((inode->i_size - 1) >> EFS_BLOCKSIZE_BITS) + 1; 116 } 117 118 rdev = be16_to_cpu(efs_inode->di_u.di_dev.odev); 119 if (rdev == 0xffff) { 120 rdev = be32_to_cpu(efs_inode->di_u.di_dev.ndev); 121 if (sysv_major(rdev) > 0xfff) 122 device = 0; 123 else 124 device = MKDEV(sysv_major(rdev), sysv_minor(rdev)); 125 } else 126 device = old_decode_dev(rdev); 127 128 /* get the number of extents for this object */ 129 in->numextents = be16_to_cpu(efs_inode->di_numextents); 130 in->lastextent = 0; 131 132 /* copy the extents contained within the inode to memory */ 133 for(i = 0; i < EFS_DIRECTEXTENTS; i++) { 134 extent_copy(&(efs_inode->di_u.di_extents[i]), &(in->extents[i])); 135 if (i < in->numextents && in->extents[i].cooked.ex_magic != 0) { 136 pr_warn("extent %d has bad magic number in inode %lu\n", 137 i, inode->i_ino); 138 brelse(bh); 139 goto read_inode_error; 140 } 141 } 142 143 brelse(bh); 144 pr_debug("efs_iget(): inode %lu, extents %d, mode %o\n", 145 inode->i_ino, in->numextents, inode->i_mode); 146 switch (inode->i_mode & S_IFMT) { 147 case S_IFDIR: 148 inode->i_op = &efs_dir_inode_operations; 149 inode->i_fop = &efs_dir_operations; 150 break; 151 case S_IFREG: 152 inode->i_fop = &generic_ro_fops; 153 inode->i_data.a_ops = &efs_aops; 154 break; 155 case S_IFLNK: 156 inode->i_op = &page_symlink_inode_operations; 157 inode_nohighmem(inode); 158 inode->i_data.a_ops = &efs_symlink_aops; 159 break; 160 case S_IFCHR: 161 case S_IFBLK: 162 case S_IFIFO: 163 init_special_inode(inode, inode->i_mode, device); 164 break; 165 default: 166 pr_warn("unsupported inode mode %o\n", inode->i_mode); 167 goto read_inode_error; 168 break; 169 } 170 171 unlock_new_inode(inode); 172 return inode; 173 174 read_inode_error: 175 pr_warn("failed to read inode %lu\n", inode->i_ino); 176 iget_failed(inode); 177 return ERR_PTR(-EIO); 178 } 179 180 static inline efs_block_t 181 efs_extent_check(efs_extent *ptr, efs_block_t block, struct efs_sb_info *sb) { 182 efs_block_t start; 183 efs_block_t length; 184 efs_block_t offset; 185 186 /* 187 * given an extent and a logical block within a file, 188 * can this block be found within this extent ? 189 */ 190 start = ptr->cooked.ex_bn; 191 length = ptr->cooked.ex_length; 192 offset = ptr->cooked.ex_offset; 193 194 if ((block >= offset) && (block < offset+length)) { 195 return(sb->fs_start + start + block - offset); 196 } else { 197 return 0; 198 } 199 } 200 201 efs_block_t efs_map_block(struct inode *inode, efs_block_t block) { 202 struct efs_sb_info *sb = SUPER_INFO(inode->i_sb); 203 struct efs_inode_info *in = INODE_INFO(inode); 204 struct buffer_head *bh = NULL; 205 206 int cur, last, first = 1; 207 int ibase, ioffset, dirext, direxts, indext, indexts; 208 efs_block_t iblock, result = 0, lastblock = 0; 209 efs_extent ext, *exts; 210 211 last = in->lastextent; 212 213 if (in->numextents <= EFS_DIRECTEXTENTS) { 214 /* first check the last extent we returned */ 215 if ((result = efs_extent_check(&in->extents[last], block, sb))) 216 return result; 217 218 /* if we only have one extent then nothing can be found */ 219 if (in->numextents == 1) { 220 pr_err("%s() failed to map (1 extent)\n", __func__); 221 return 0; 222 } 223 224 direxts = in->numextents; 225 226 /* 227 * check the stored extents in the inode 228 * start with next extent and check forwards 229 */ 230 for(dirext = 1; dirext < direxts; dirext++) { 231 cur = (last + dirext) % in->numextents; 232 if ((result = efs_extent_check(&in->extents[cur], block, sb))) { 233 in->lastextent = cur; 234 return result; 235 } 236 } 237 238 pr_err("%s() failed to map block %u (dir)\n", __func__, block); 239 return 0; 240 } 241 242 pr_debug("%s(): indirect search for logical block %u\n", 243 __func__, block); 244 direxts = in->extents[0].cooked.ex_offset; 245 indexts = in->numextents; 246 247 for(indext = 0; indext < indexts; indext++) { 248 cur = (last + indext) % indexts; 249 250 /* 251 * work out which direct extent contains `cur'. 252 * 253 * also compute ibase: i.e. the number of the first 254 * indirect extent contained within direct extent `cur'. 255 * 256 */ 257 ibase = 0; 258 for(dirext = 0; cur < ibase && dirext < direxts; dirext++) { 259 ibase += in->extents[dirext].cooked.ex_length * 260 (EFS_BLOCKSIZE / sizeof(efs_extent)); 261 } 262 263 if (dirext == direxts) { 264 /* should never happen */ 265 pr_err("couldn't find direct extent for indirect extent %d (block %u)\n", 266 cur, block); 267 if (bh) brelse(bh); 268 return 0; 269 } 270 271 /* work out block number and offset of this indirect extent */ 272 iblock = sb->fs_start + in->extents[dirext].cooked.ex_bn + 273 (cur - ibase) / 274 (EFS_BLOCKSIZE / sizeof(efs_extent)); 275 ioffset = (cur - ibase) % 276 (EFS_BLOCKSIZE / sizeof(efs_extent)); 277 278 if (first || lastblock != iblock) { 279 if (bh) brelse(bh); 280 281 bh = sb_bread(inode->i_sb, iblock); 282 if (!bh) { 283 pr_err("%s() failed at block %d\n", 284 __func__, iblock); 285 return 0; 286 } 287 pr_debug("%s(): read indirect extent block %d\n", 288 __func__, iblock); 289 first = 0; 290 lastblock = iblock; 291 } 292 293 exts = (efs_extent *) bh->b_data; 294 295 extent_copy(&(exts[ioffset]), &ext); 296 297 if (ext.cooked.ex_magic != 0) { 298 pr_err("extent %d has bad magic number in block %d\n", 299 cur, iblock); 300 if (bh) brelse(bh); 301 return 0; 302 } 303 304 if ((result = efs_extent_check(&ext, block, sb))) { 305 if (bh) brelse(bh); 306 in->lastextent = cur; 307 return result; 308 } 309 } 310 if (bh) brelse(bh); 311 pr_err("%s() failed to map block %u (indir)\n", __func__, block); 312 return 0; 313 } 314 315 MODULE_LICENSE("GPL"); 316